Is there a canon explanation for how Proton Torpedoes were able to turn 90 degrees at the end of Star Wars: ANH

Question

Based on this question: Why did Luke need a targeting computer in the first place?

Proton Torpedoes launched from Luke's X-Wing were able to change direction 'on a dime' 90 degrees to get into Death Star's thermal exhaust shaft.

It seems intuitively obvious that the cause of that was technological (since Luke had nowhere near Force training at the time to be able to cause the turn).

Is there any sort of official Canon explanation for how the torpedoes turned?

E.g., was it some capability of torpedoes' propulsion? Forcefields from an X-Wing? Some interplay between a torpedo and Death Star's technology as TangoOversway's answer to that question alluded to being a possibility? Some other mechanism?

Please note that "programmed to turn in advance by X-Wing's targeting computer" is not an answer, as I'm looking specifically for what the mechanism for ability to execute the turn, NOT why the turn happened when it happened.

Answer 1

Short answer: They don't really "turn 90 degrees". Or rather, they probably weren't supposed to.

In the fourth draft (the one just prior to filming) of the script, Lucas gives us a hint about how he envisioned the Proton Torpedoes working:

                              DODONNA
                Your approach will not be easy.  You
                must maneuver straight in
                down this shaft, level off in the
                trench and skim the surface to this
                point.  The target is only two meters
                across.  It will take a very precise
                hit at exactly ninety degrees to get
                into the reactor system.  And only a
                direct hit will set up a chain
                reaction.  The shaft is ray shielded,
                so you'll have to use proton torpedoes.

I think by "ninety degrees" that Lucas was probably imagining that the pilot had to be directly above the exhaust port in order for it to drop go all the way down into the reactor. That might make sense when you're writing something, but it's obviously harder to ignore the laws of inertia when someone asks you to animate it. (You may interpret it differently, though.)

The SFX team apparently took this problem and envisioned them more "realistically" as something akin to traditional bombs. You can see this in the movie for yourself in one of Dan O'Bannon's tactical displays:

It clearly shows the idea was that the pilot was supposed to "drop" the torpedoes into the exhaust port, like a real world bomb.

Later in the movie, when Luke actually fires his Proton Torpedoes into the Death Star, we see them shoot straight into the distance, and then "drop" into the exhaust vent. This implies some further input from Luke, but actually he turns off his targeting computer in order to manually decide when to fire his torpedoes into the exhaust port, and there doesn't appear to be any further input from him after that at all. Very confusing.

Indeed, if you slow down the infamous shot in question, you can see that the animator seemed want the torpedoes to appear to be falling... it's the just animation happens too quickly you don't see it. (And the previous shot of them travelling in a straight line, like a laser, doesn't really help.)

I created this animated GIF, slowing down all 16 frames of the animation, so you can see this for yourself:

So it appears to be a somewhat inconsistent interpretation born out of probably what was only a rough idea in the script to begin with (Lucas was never one for getting bogged down in technical details of his universe), rather than anything deliberately thought out.

Maybe George Lucas could fix this issue in one last "Special Edition"? :) (Just kidding, please don't kill me.)

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Expanded Universe Explanation

Of course, that's just one canon. If you're open to letting other authors interpret how Proton Torpedoes work, and are prepared to enter the murky (and often contradictory) "Expanded Universe", then there's more answers waiting for you.

Noting their apparently strange behaviour in the original movie, it seems that most EU authors have imagined Proton Torpedoes to be simple homing missiles with the additional ability of manual remote control.

Here's some samples from the EU novels:

• X-Wing: Rogue Squadron (1996), Michael A. Stackpole

"Corran switched over to proton torpedo target control."

• Jedi Trial (2004), David Sherman and Dan Cragg

"Gunnery officer, mark that target for proton torpedo salvo. Deactivate the homing system. Use line-of-sight guidance system. I want these babies dead on."

In the games (X-Wing, Rogue Squadron, etc.), however, they are treated differently yet again: More like standard slow-but-powerful homing missiles, with no manual guidance. In the X-Wing Miniatures board game they are also treated like homing missiles (requiring a player to "lock" on a target before they can be fired). This is more likely born out of the need for gaming mechanics, however.

Despite this general consensus about their behaviour, other EU sources are contradictory. For example, the aforementioned Jedi Trial states that Proton Torpedoes were first used in the "Clones Wars", yet Anakin's big yellow Starfighter at the end of The Phantom Menace is said to be equipped with them. Furthermore, Star Wars: Knights of the Old Republic II, set thousands of years before the events of the movies, makes mention of them as well.

Basically, with the EU you pretty much get to choose your canon, but most of the time they're considered to be homing missiles, with the ability for manual guidance. (With this interpretation, Luke turning off his targeting computer allowed him to manually guide the missiles down the exhaust port.)

Answer 2

I always assumed that the Torpedoes were 'sucked' in. Although thinking about it, the port is an exhaust port. Perhaps some complex pump system causes a pressure differential after exhausting waste gas.

Unfortunately I don't have any 'evidence' for (or against) this, if anyone does, I'd appreciate an edit to that effect.

Quoting from this answer

The original novel by Lucas states, as an extension to the dialogue heard in the movie, something along the lines of "the shaft would be rendered useless by particle shielding; however, it is completely ray-shielded". This further increases my confidence that the "thermal exhaust" consists primarily of matter and not energy.

So it seems likely that the port was venting matter of some kind that could have created a pressure differential sucking those torpedoes down.

Answer 3

Wookieepedia states (without attribution) that proton torpedoes have the ability to turn 90 degrees inside of a meter, with an accompanying image of just what you're talking about.

It seems to me that it wasn't merely getting them into the vent that was the trick, it was that the port was an opening to a path to the reactor. So, practically speaking, the pilot needs to get the torpedoes close enough to the vent to prevent them from being countermeasured or otherwise done away with, and then the internal guidance programming would take over.

It's FAR from canon, but in the old X-Wing and Tie Fighter games, proton torpedoes were target seeking weapons with their own guidance systems.

Answer 4

This was changed from the book version, as the pilots were originally told that they would have to approach the exhaust port at a precise 90 degree angle, precisely fire the torpedoes, then veer away before crashing into the death star itself, both of which are what made it near impossible save for the most skilled pilots, especially while being pursued by Tie Fighters, avoiding turbo laser fire, etc.

Here is the exact quote I copied from another commenter;

You must maneuver straight in down this shaft, level off in the trench, and skim the surface to-this point. The target is only two meters across. It will take a precise hit at exactly ninety degrees to reach the reactor systematization. And only a direct hit will start the complete reaction. "I said the port wasn't particle-shielded. However, it is completely ray-shielded. That means no energy beams. You'll have to use proton torpedoes.

I always assumed that the torpedoes were programmed to turn at 90 degree's and that the real "trick" was the PRECISE moment of firing, which Luke was able to do because of the force and Obi-Wan helping him out. This is why when they showed the targeting computers you saw the two vertical lines closing and the distance counting down to firing time.

I have not come across a specific mention in the books or any other source material I have read as to what the exact MECHANISM is on how or why the torpedoes were able to turn 90 degree's, but they are target lock homing weapons. This I also know to be true from the X-Wing video games. If I have a chance to look through one of the Star Wars Tech manuals I will check it out.

Answer 5

Perhaps it had something to do with the positive charge on the Proton Torpedo (thus "Proton" Torpedo) acting with the magnetic field of the exhaust port. The walls could be positively charged while the Death Star core could have a strong negative charge, resulting in the positively charged matter in the Proton Torpedo to be drawn to the exhaust port but repelled from the shaft.

Answer 6

Well I will give an answer just based on I haven't seen this answer appear on this page yet, at least not as I interpreted the question. First of all the battle to destroy the Death Star (is this actually the second Death Star?) takes place in outer space. Unless the Death Star has an artificial atmosphere, which was not alluded to in the movies, that would mean that the trajectory of the proton torpedoes in question at least until entering the thermal vent shaft would take place in a vacuum.

I found a .pdf of a second edition of the Star Wars Sourcebook by West End Games, which states that in their section on armaments,

"Proton Torpedoes...Unlike heavier space bombardments used by turbolasers mounted in immense Star Destroyers, these weapons are effective against ray and energy shielded targets...Proton torpedoes carry a proton-scattering energy warhead."

Because these warheads I think from this quote are implied to have mass, the only way according to physics to be able to turn these warheads, even if they had an internal steering device, would need to be acted on by a force... i.e. a little rocket booster would have to be turned on mid-flight to correct the direction of the warhead (objects in space will continue to move in a straight line unless acted on by a force (Newton's first law)). According to the graphic that @Django Reinhardt created I don't see those adjustment boosters, at least they're not obvious.

So that's my first point. My second point is that again I am assuming that these proton torpedo warheads have significant weight and my follow up on that would be that the Death Star, due to it's significant size may be exerting a considerable force of gravity, similar to our moon does on our Earth. Therefore, especially given the close distance of Luke's ship it may just be a simple problem of a heavy object falling into a field of gravity, similar to a plane that is moving forward with a velocity v and drops a package, the package then continues moving forward with a velocity v, and falls to Earth because it is pulled by the force of the Earth's gravity downward. It therefore falls in a sort of an arc downward, which may have been what the original plan for the proton torpedoes' flight.

Answer 7

According to the Star Wars: Blueprints - Rebel Edition factbook, The Proton Torpedo consists of four primary components; A Propellant Cylinder, an Energy Envelope Projector, an Ignition Charge and a Homing Sensor (along with the Explosive Payload, obviously).

Since we can disregard the Payload, the Ignition Charge and the Homing Sensor as being the means by which the torpedo can turn, it stands to reason that it's either the Propellant Cylinder or the Energy Envelope Projector that allow tight maneuvering.

The Essential Guide to Weapons and Technology describes the Energy Envelope as a...

"Protective energy envelope to prevent accidental detonation caused by collisions with debris or near misses by laser cannon blasts"

... which leaves only the propellant tube (vectored thrust?) as the means by which the torpedo can execute turns, guided by the homing sensor.

Answer 8

They seem to follow more of a parabolic arch. The screen time is so short, the eye creates the illusion of a sharp turn. Lacking a guidance system, it stands to reason that the torpedoes had a preprogrammed trajectory already established. And the display on the targeting computer seems to reinforce this as more of an optimal firing range rather than a target to lock on. Given the high speed of the fighters, it seems even the computers couldn't postulate the ideal firing time correctly. Seems to me, when Luke opened himself to the Force, it not only told him where to shoot, but when.

Answer 9

This merely seems to be a question of converting horizontal inertia to vertical movement. Proton torpedoes have been seen in illustration to have a gyroscopic guidance system. Guided ordnance in space would have the same mechanics of a simple shuttle as far as maneuvering is concerned. Timing the Rotation of the torpedo and then the subsequent main thruster firing along with pitch correction to compensate for the forward inertial movement would require an extensive knowledge of the behavior of the particular projectile (perimeter trim thrusters, lag time if these particular torpedoes are preset to home after "dropping"). Wait... Use the force, Luke.